Cylindrical wire cages are used to reinforce the walls of concrete pipes. The wire cages are placed within forms used with a packerhead concrete pipe making machines or vibrating core pipe making machines. Structures called cage positioners are used to locate the cages within the forms during the forming of the concrete pipe. The reinforcing cages must be centrally positioned in the forms so that they will be properly imbedded within the concrete to ensure uniform integrity of the pipe walls.
A cage positioner located within a reinforcing cage that moves upwardly with the packerhead to concentrically position the cage relative to the packerhead is disclosed by L. C. Gourlie et al in U.S. Pat. No. 3,262,275. A plurality of hydraulic piston and cylinder assemblies are mounted on the packerhead shaft. Shoes mounted on rods connected to the pistons slide upwardly along the cage during the forming of the pipe. W. Muller in U.S. Pat. No. 4,505,658 discloses a mechanism for centering a reinforcing cage within a form for making a concrete pipe with a packerhead concrete pipe making machine. The mechanism has a member which moves through a slot in the form and engages the cage to center the cage relative to the form. A spring biased over center mechanism retains the member in the cage engaging position. The centering members move away from the cage under the pressure of the concrete being formed into a pipe by the packerhead. Tucker et al in U.S. Pat. No. 4,710,115 discloses a cage positioning device mounted on the form to locate the concrete pipe reinforcing cage within the form. The device has a slide member guided with a frame mounted on the form for movement into engagement with the cage. The member moves through a slot in the side wall of the form. A piston and cylinder assembly mounted on the form operates a cam connected to the side member so that on operation of the piston and cylinder assembly, the slide member can be selectively moved into and out of engagement with the cage. These cage positioners have separate structures that must be adjustable to ensure the proper centering of the cage in the form. The adjusting structures and moving parts of the cage positioner increase costs and are subject to substantial wear and breakage when used with concrete pipe making machines and particularly with vibrating core pipe making machines.